A police officer in Rome guards an ancient statue recovered with thousands of other artifacts stolen from Italy. Concern about looting of archaeological sites worldwide has intensified in the wake of reports that Islamist groups have looted and trafficked in antiquities, possibly to fund terrorism. (Cover: AFP/Getty Images/Alberto Pizzoli)

Reports that the Islamist group ISIS may be funding terrorism by selling looted artifacts from war-torn Iraq and Syria have spurred calls for a new crackdown on the illicit antiquities trade. The United States has banned antiquities imports from Iraq and Syria, and the European Union is considering requiring proof that antiquities entering Europe were legally exported from their home countries, as Germany did last year. Archaeologists favor tougher documentation requirements, but antiquities dealers say such rules are impossible to meet and could destroy the legitimate market. Meanwhile, efforts to have ancient objects returned to their country of origin continue to spark controversy. For years Greece has demanded that Britain relinquish sculptures taken from the Parthenon in the 19th century. In the United States, some archaeologists complain that a 1990 law requiring museums and federal agencies to return skeletal remains of Native Americans to tribes for reburial prevents scientific study of North America's earliest inhabitants.